Such lines are used, for example, for connecting movable devices to a voltage or signal source. Movable devices can be, for example, cranes, machine tools and robots. The lines must be capable of being loaded mechanically, with a flexural strength remaining uniform over a long period. They should also remain easily flexible within a wide temperature range which is, for example, between −40° C. and +80° C. If the lines are used, for example, as drag chain lines in automation technology, they must also survive without damage movements at increased speeds of up to 5 m/sec in the horizontal direction and corresponding accelerations of up to 50 m/sec2 continuously even with relatively great lengths of up to 50 m. “Continuously” means, for example, up to 5 million bending cycles in this context.
The known line according to the EP 1041585 B1 initially mentioned is constructed as a flexible electric power line which has a central core around which power wires, at least one control line and at least one data line are stranded. The core has a central strength element consisting of plastic, over which a sheathing of a cross-linked material is provided in which an indentation extending over the entire axial length of the core is provided which is adapted for each stranded-around element to the contour of the latter. Apart from power and control commands, measurement data can also be transmitted, for example, by means of this electric power line. The good flexibility of the electric power line is supported by the special construction of the core, in the indentations of which adapted to the respective stranded-around element, these elements can slide when the electric power line is bending. This electric power line has been successful in practice. Measures of how a sliding mobility of the stranded elements relative to the core is to be achieved and whether a functional capability of the electric power line is to be maintained even with a great length during movements at high speed and acceleration are not mentioned in the document.